fdt: Update Makefile rules with the new OF_REAL Kconfig

Simplify some of the Makefile rules using this Kconfig.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/lib/Makefile b/lib/Makefile
index dfe772a..09e380e 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -80,10 +80,7 @@
 obj-$(CONFIG_LIBAVB) += libavb/
 
 obj-$(CONFIG_$(SPL_TPL_)OF_LIBFDT) += libfdt/
-ifneq ($(CONFIG_$(SPL_TPL_)BUILD)$(CONFIG_$(SPL_TPL_)OF_PLATDATA),yy)
-obj-$(CONFIG_$(SPL_TPL_)OF_CONTROL) += fdtdec_common.o
-obj-$(CONFIG_$(SPL_TPL_)OF_CONTROL) += fdtdec.o
-endif
+obj-$(CONFIG_$(SPL_TPL_)OF_REAL) += fdtdec_common.o fdtdec.o
 
 ifdef CONFIG_SPL_BUILD
 obj-$(CONFIG_SPL_YMODEM_SUPPORT) += crc16.o